Self-Healing Cement—Novel Technology To Achieve Leak-Free Wells

Abstract

TX 75083-3836 U.S.A., fax 1.972.952.9435. AbstractThere is a very large number of wells worldwide that leak or have sustained casing pressure (SCP). In Central Europe and the Middle East there are hundreds of wells with reports of trapped pressure that cannot be bled off. In the US and Canada there are thousands of wells leaking to surface, which may or may not be discharged to the atmosphere. Furthermore, 25% of all wells in the Gulf of Mexico have measurable sustained casing pressure. Additionally, remedial work fixing issues relating to cement failure has been estimated to be more than $50M a year in the US alone.Throughout the lifecycle of a well, planned cycle or operational changes can contribute to unknown damage to the cement sheath integrity that is hard to identify or locate, including the generation of a microannulus. Within flow paths, hydrocarbons can either migrate to surface, or become trapped below the wellhead leading to pressure build-up. Typical events occur during cementing, while perforating or stimulating, throughout the subsequent production, and even after abandonment. These can easily create this loss of cement integrity.This paper describes a novel isolation system that is activated only when a cement integrity problem occurs. The system will automatically and rapidly form a complete hydraulic barrier by swelling in the presence of hydrocarbon flow. Once activated, it will seal the damaged zone, and will even be able to be activated again, should further damage occur again during production or abandonment. The system has properties equivalent to conventional cement systems, and requires no modifications to standard surface equipment.High pressure static and dynamic laboratory tests highlight the ability of the system to rapidly shut off gas flows within 30 minutes. Field tests have also highlighted the robustness of the system, with a number of wells currently using the system remaining leak-free.

Development of Self-Healing Cement Slurry through the Incorporation of Dual-Encapsulated Polyacrylamide for the Prevention of Water Ingress in Oil Well

“…The swelling properties of the prepared cement cores were investigated using an annular expansion mold [ 39 ]. Briefly, the cement slurry with additives was poured into the annulus between the two rings and allowed to set for 48 h. Then the mold was put in a water bath for 8 h. Upon absorbing water, the cement core swells thereby increasing the distance between the two slits in the outer periphery.…”

Review of studies on plugging compositions creation with controlled rheological properties and the ability to restore fluidity for completion, workover and abandonment of oil and gas wells

“…В работах исследовательского коллектива нескольких лабораторий под руководством P. Cavanagh [28,29] описывается новый подход к изоляции и герметизации скважин за счет активизации самовосстанавливающихся компонентов цемента (их набухания) в присутствии потока углеводородов при возникновении проблемы целостности цементной матрицы. После активации подобных процессов при контакте с углеводородами поврежденная зона закупоривается и может быть снова регенерирована в случае повторного или дальнейшего повреждения.…”

Swellable elastomeric HNBR–MgO composite: Magnesium oxide as a novel swelling and reinforcement filler

“…Their autonomous swelling is employed in a variety of applications, particularly in areas where continuous human monitoring and timely intervention is difficult or impossible. Some examples include microfluidic valves for flow control [1], self-healing cement to maintain cement integrity [2], and swell packers for sealing applications in the oilfield environment [3][4][5][6]. Unlike other applications that use only small quantities of swellable elastomers, swell packer applications involve large amounts of the elastomers corresponding to the wellbore geometries to sustain a large amount of load.…”